The present invention is related to a drive circuit for controlling the conductive and nonconductive states of a P-channel FET transistor.
The use of P-channel MOSFETS in power conversion circuits requires a fairly complex drive scheme in order to achieve efficient utilization of the device. The traditional methods for realizing this function require the use of high wattage resistors for controlling the switching of the P-channel MOSFET. One application of the P-channel MOSFET is in switched mode power converter circuits such as buck or step down converters. Using previous or traditional drive schemes, power losses incurred could exceed the total output power delivered by the buck power converter. Previous schemes used two active devices to control the P-channel MOSFET, one to turn the FET on and one to the turn the FET off. Two active devices in the control requires the need for additional support components for circuit operability. The total component count affects circuit reliability as well as cost and card space required.
It is an object of the present invention to provide a drive circuit for a P-channel MOSFET that has lower power losses.
It is a further object of the present invention to provide a drive circuit for P-channel FET with higher reliability, lower cost and which requires less card space to implement.